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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 18 |
| 5 | 523 |
| 6 | 44884 |
| 7 | 227838935 |
| 8 | 1086696880188 |
| 9 | 1566338449874827101 |
| 10 | 694432397394116143569646 |
[1,2,5,18,523,44884,227838935,1086696880188, 1566338449874827101,694432397394116143569646] |